Complex machines, such as internal combustion engines, include internal operating environments characterized by high temperatures and high pressure. Components operating in such environments are often coated to provide hard surfaces with low friction properties. Liquid hydrocarbons (e.g., fuel, oil and lubricants) are circulated within the environments during operation. Such liquid hydrocarbons often include additives to optimize the performance of the machine and preserve the coated components. The additives add cost to the liquid hydrocarbons, and may result in undesirable emissions and waste disposal issues.
There are a variety of known processes for coating products for use in such operating environments. Physical vapor deposition (PVD) is one example of such a coating process. PVD is a general term used to describe any of a variety of methods to deposit thin films or coatings, by the condensation of a vaporized form of the material onto a substrate. There are several different types of PVD processes, including: sputtering, cathodic arc deposition, pulsed laser deposition, evaporative deposition, electron beam physical vapor deposition and magnetron sputtering. Sputtering is often used when it is desirable to deposit an alloy of two or more materials at a time. Magnetron sputtering may be used to control the deposition area and to achieve high deposition rates.
U.S. Pat. No. 7,211,323 to Erdemir et al. discloses examples of hard, low friction nitride coatings formed using PVD techniques such as cathodic arc discharge, ion-plating, magnetron sputtering and laser ablation.